Indicator dilution methods will be used to find appropriate diffusion limited indicators for measurement of pulmonary capillary permeability. Measurements will be made of the cellular and inter-stitial volumes of an isolated and perfused lung preparation. Changes will be made in arterial and venous pressures, plasma protein concentration and osmolality. Both edematous and normal lungs will be studied. An external scanning procedure will be used to measure pulmonary congestion and edema on a regional basis. Control studies will continue in patients receiving indicator for brain scans. Cardiac and noncardiac pulmonary edema will be monitored.